﻿THE 
  BRAIN 
  OF 
  THE 
  LOCUST. 
  229 
  

  

  the 
  face 
  from 
  before 
  bade 
  wards 
  ; 
  in 
  catting 
  thus 
  through 
  the 
  head, 
  twelve 
  

   sections 
  were 
  made 
  before 
  the 
  front 
  part 
  of 
  the 
  braiu 
  was 
  touched, 
  the 
  

   thirteenth 
  grazing 
  the 
  front 
  of 
  the 
  brain. 
  Section 
  14 
  passed 
  through 
  the 
  

   anterior 
  part 
  of 
  both 
  caliccs, 
  but 
  did 
  not 
  touch 
  the 
  stalk 
  of 
  the 
  mush- 
  

   room 
  body 
  (these 
  terms 
  will 
  be 
  explained 
  farther 
  on). 
  It 
  passed 
  through 
  

   the 
  central 
  region 
  of 
  each 
  hemisphere, 
  including 
  the 
  front 
  part 
  of 
  the 
  

   trabecule 
  or 
  base 
  of 
  the 
  stalk 
  of 
  the 
  mushroom 
  body. 
  The 
  section 
  passed 
  

   through 
  the 
  commissural 
  lobes, 
  the 
  lower 
  third 
  being 
  composed 
  of 
  ganglion 
  

   cells, 
  but 
  the 
  substance 
  of 
  the 
  commissure 
  itself 
  is 
  filled 
  with 
  the 
  ball- 
  

   like 
  masses 
  of 
  " 
  marksubstanz." 
  The 
  commissures 
  to 
  the 
  subcesophageal 
  

   ganglion 
  were 
  not 
  touched, 
  and 
  do 
  not 
  appear 
  in 
  the 
  section, 
  since 
  they 
  

   arise 
  from 
  the 
  back 
  of 
  the 
  brain. 
  

  

  In 
  section 
  15 
  no 
  additional 
  organs 
  are 
  exposed. 
  In 
  section 
  16 
  (PI. 
  

   X, 
  Fig. 
  1) 
  the 
  trabecular 
  are 
  seen, 
  when 
  magnified 
  225 
  diameters, 
  to 
  

   be 
  composed 
  of 
  ascending 
  fibers, 
  which 
  form 
  the 
  base 
  or 
  origin 
  of 
  the 
  

   double 
  stalk 
  of 
  the 
  mushroom 
  body. 
  

  

  Section 
  17 
  (PI. 
  X, 
  Fig. 
  2) 
  is 
  the 
  most 
  important 
  of 
  all 
  the 
  sections, 
  as 
  

   the 
  entire 
  mushroom 
  body 
  and 
  the 
  central 
  body 
  are 
  cut 
  through, 
  together 
  

   with 
  the 
  antennal 
  lobes, 
  and 
  the 
  commissural 
  lobes, 
  and 
  also 
  the 
  origin 
  

   of 
  the 
  optic 
  nerves. 
  

  

  In 
  section 
  18 
  (PI. 
  X, 
  Fig. 
  1) 
  the 
  double 
  nature 
  of 
  the 
  stalk 
  of 
  the 
  

   mushroom 
  body 
  is 
  seen 
  ; 
  the 
  optic 
  lobes 
  are 
  now 
  well 
  marked, 
  and 
  the 
  

   razor 
  grazed 
  the 
  back 
  of 
  the 
  commissural 
  lobes, 
  as 
  well 
  as 
  the 
  inner 
  

   side 
  of 
  the 
  optic 
  ganglion. 
  The 
  section 
  passed 
  behind 
  the 
  trabecular 
  and 
  

   the 
  base 
  of 
  the 
  stalk 
  aud 
  through 
  the 
  back 
  of 
  the 
  central 
  body. 
  The 
  

   calices 
  are 
  each 
  seen 
  to 
  be 
  so 
  furrowed 
  and 
  uneven 
  as 
  to 
  appear 
  in 
  the 
  

   section 
  as 
  two 
  separate 
  portions. 
  Two 
  important 
  nerves 
  (PI. 
  X, 
  Fig. 
  

   4, 
  p. 
  a. 
  n.) 
  are 
  seen 
  to 
  arise 
  from 
  the 
  commissural 
  lobes, 
  and 
  to 
  pass 
  

   upwards, 
  ending 
  on 
  each 
  side 
  of 
  the 
  upper 
  furrow, 
  near 
  the 
  origin 
  of 
  

   what 
  we 
  think 
  are 
  possibly 
  the 
  ocellar 
  nerves 
  (o. 
  c. 
  n.f). 
  

  

  Section 
  19 
  (PL 
  XI, 
  Fig. 
  1) 
  passed 
  through 
  the 
  back 
  of 
  the 
  brain 
  (com- 
  

   pare 
  Fig 
  4. 
  of 
  the 
  same 
  plate, 
  which 
  represents 
  a 
  vertical 
  or 
  longitudinal 
  

   section 
  of 
  the 
  brain), 
  through 
  the 
  oesophageal 
  commissures, 
  and 
  the 
  back 
  

   edge 
  of 
  the 
  calices, 
  while 
  the 
  antennal 
  lobes 
  and 
  a 
  part 
  of 
  the 
  optic 
  lobes 
  

   are 
  well 
  seen 
  in 
  the 
  section. 
  A 
  transverse 
  commissural 
  nerve 
  (t 
  c 
  n) 
  con- 
  

   nects 
  the 
  two 
  antennal 
  lobes, 
  and 
  the 
  commissural 
  nerves 
  are 
  seen 
  to 
  

   cross 
  at 
  the 
  bottom 
  of 
  the 
  furrow. 
  

  

  Section 
  20 
  (PI. 
  XI, 
  Fig. 
  2), 
  which 
  passes 
  through 
  the 
  extreme 
  back 
  of 
  

   the 
  brain, 
  shows 
  in 
  this 
  plane 
  four 
  transverse 
  bundles 
  of 
  nerve 
  fibers 
  

   connecting 
  the 
  two 
  hemispheres, 
  i. 
  e., 
  the 
  inferior 
  (inf. 
  n.), 
  two 
  median 
  

   (m. 
  n.) 
  and, 
  a 
  superior 
  nerve 
  (sup. 
  n.). 
  In 
  this 
  section 
  the 
  relations 
  

   of 
  the 
  optic 
  ganglion 
  and 
  eye 
  to 
  the 
  brain 
  are 
  clearly 
  seen, 
  the 
  optic 
  

   ganglion 
  being 
  situated 
  in 
  the 
  posterior 
  region 
  of 
  the 
  brain. 
  It 
  will 
  

   also 
  be 
  seen 
  that 
  the 
  two 
  hemispheres 
  are 
  at 
  this 
  point 
  only 
  connected 
  

   anteriorly. 
  

  

  In 
  sections 
  22, 
  23, 
  and 
  24 
  the 
  brain 
  nearly 
  disappeared, 
  and 
  only 
  the 
  

  

  